Pipe bender



Jan. 30, 1962 E. c. SWANSON PIPE BENDER 2 Sheets-Sheet 1 Filed Feb. 27,1957 IVENTOR.

Jan. 30, 1962 E. c. SWANSON PIPE BENDER 2 Sheets-Sheet 2 Filed Feb. 27,1957 ilnited States Patent 9 3,018,818 PlPE BENDER Edwin C. Swanson,Rockford, Ill., assignor to Greenlee Bros. & Co., a corporation ofIllinois Filed Feb. 27, 1957, Ser. No. 642,839 8 Claims. (Cl. 153-48)This invention relates to pipe benders, and particularly to pipe bendersof the type having a pair of spaced pipe engaging rollers, a forceapplying ram reciprocable toward and away from a midpoint between therollers, and a pipe bending shoe structure connected to the ram forproducing a bend in the mid-section of a length of pipe positionedagainst the rollers.

It is a general object of the invention to provide a new and improvedpipe bender of the type described.

It is a more specific object of the invention to provide a new andimproved pipe bending shoe structure for use in a bender of the typedescribed.

Another object is to provide a new and improved bending shoe structureof the character described, including an adapter connected to the ram,and a bending shoe detachably connected to the adapter in a manner suchthat ram forces are distributed over a substantial length of the bendingshoe so that a number of different size bending shoes may be constructedof relatively lightweight material, as compared to the material of theadapter, for use with the adapter, thereby providing a readily portableand versatile bending apparatus.

It is also an object of the invention to provide a new and improved pipebender of the type described having indicia provided thereon for use indetermining when the desired degree of pipe bend has been produced.

Another object is to provide, in a bending shoe structure, new andimproved means for dislodging the pipe from the shoe after bending. 1

A further object is to provide, in a bender of the type described, a newand improved mounting pin assembly for mounting the pipe-engagingrollers to be readily removable and replaceable. I

Other objects and advantages will become readily apparent from thefollowing detailed description taken in connection with the accompanyingdrawings, in which:

FIG. 1 isa plan view of a pipe bender embodying the principles of thepresent invention, with a portion of the top frame plate broken away tobetter illustrate the bending shoe structure;

FIG. 2 is a longitudinal sectional view of the bender illustrated inFIG. 1, taken at about the line 2-2 of FIG. 1;

FIG. 3 is a front elevational view of the bender illustrated in FIGS. 1and 2;

FIG. 4 is an enlarged plan view illustrating in detail the constructionof the adapter forming a part of the bending shoe structure included inthe bender of FIGS. 1, 2 and 3;

FIG. 5 is a front elevational view of the adapted illustrated in FIG. 4;

FIG. 6 is an end elevational view of the adapter illustrated in FIGS. 4and 5, also showing in section the bending shoe illustrated in FIG. 1,the section through the bending shoe being taken at about the line 6-6of FIG. 1;

FIG. 7 is an enlarged front elevational view of the bending shoe;

FIG. 8 is an enlarged sectional view, taken at about the line 88 of FIG.1, illustrating the pin mounting assembly for mounting the pipe engagingrollers utilized in the bender illustrated in FIGS. 1, 2, and 3;

FIG. 9 is a bottom plan view of the pin mounting 3,5a18,818 PatentedJan. 30, 1962 assembly illustrated in FIG. 8, taken at about line 9-9 ofFIG. 8; and

FIG. 10 is an enlarged sectional view through the bending shoe, taken atabout the line 10-40 of FIG. 1, illustrating details of the meansprovided for removing pipe from the bending shoe after bending.

While an illustrative embodiment of the invention is shown in thedrawings, and will be described in detail herein, the invention issusceptible of embodiment in many different forms, and it should beunderstood that the present disclosure is to be considered as anexemplification of the principles of the invention and is not intendedto limit the invention to the embodiment illustrated. The scope of theinvention will be pointed out in the appended claims.

Referring'now to the drawings, and particularly to FIGS. 1,2, and 3, fora detailed description, as illustrated, the invention is embodied in apipe bender including a pair of frame plates 10 and 11 of generallytriangular shape mounted in overlying spaced apart relationship in orderto receive therebetween a length of pipe to be bent. A pair ofpipe-engaging rollers 12, similarly formed, are mounted in spaced apartrelationship between the plates '10 and 11, with the roller axesextending in a direction normal to the planes of the plates. The frameplates 10 and 11 support a ram device, generally designated 13,including a force applying ram reciprocable between the plates towardand away from a midpoint between the pipe engaging rollers 12. A pipebending shoe structure, generally designated 14, is attached to theforce applying ram and includes a pipe engaging portion effective toproduce a bend in the mid-section of a length of pipe positioned betweenthe frame plates against the pipe-engaging rollers.

As illustrated, the frame plates 10 and 11 are of generally triangularshape and are rigidly held in overlying, spaced-apart relationship bymeans of a pair of spacers 16 (FIG. 3), which are positioned between theplates adjacent the ram device 13 and to which the plates are secured bymeans such as screws 17.

The pipe-engaging rollers 12 are similarly formed and each may berecessed on its periphery, arcuately, to receive a portion of the outercircumference of a length of pipe to be positioned thereagainst. Asillustrated, each of the rollers 12 includes, at angular spacedpositions thereon, four arcuate recesses 19, 20, 21 and 22 (FIGS. 2, and3) of different radii, so that by angularly positioning the rollers,they are adapted for receiving pipes of different sizes.

The pipe engaging rollers 12 are mounted between the frame plates bymeans of roller pin mounting assemblies 24 (FIGS. 8 and 9) which serveto rotatably 4 support the rollers and which are readily removable andreplaceable in order to permit quick removal of the rollers 12 and readysubstitution therefor of rollers having differently formed pipereceiving recesses. As illustrated in FIG. 8, the pipe-engaging rollersare each formed with a central axial bore 25, and the pin mountingassembly 24 includes a main pin body 26 of cylindn'cal shape receivablein the bore 25 so that the roller is rotatable on the pin body. As seenin FIGS. 1 and 8, the frame plate 10 is formed with a plurality of pairsof circular apertures 27, 28, 29, 30, etc. of a diameter similar to theroller bore 25 and also for receiving the pin bodies are mounted one ineach of the apertures 27, or one in each of the apertures 28, etc. Thedifferent pairs of apertures 27, 28, etc. are provided for repositioningthe pipe-engaging rollers to accommodate pipe lengths of different sizediameters. For example, the apertures 27 may be utilized to position thepipe-em gaging rollers for bending a pipe of 4" diameter, the apertures28 for pipe of 3 diameter, and so on. The degree of bend produced in thepipe is normally determined by the length of the ram stroke; and theradius of bend produced in the pipe is normally determined by thecurvature of the pipe engaging face of the bending shoe.

Referring again to FIG. 8, the upper end of the pin body 26 is enlargedas illustrated at 33 to form an annular shoulder or abutment 34engageable with the top of the upper frame plate to limit movement ofthe pin body through the plates and through the pipe-engaging rollers.Once positioned, the pin body 26 may be locked in place by meansincluding a locking shaft 35 rotatable in an axial bore 36 eccentricallypositioned in the pin body 26 and extending throughout the lengththereof. Near its lower end, the locking shaft 35 is provided with anintegral, radially projecting locking lug 37. The locking lug 37 ismovable in a recess 37a extending transversely across the pin body adistance slightly more than half the diameter of the pin body. Asillustrated in FIGS. 8 and 9, the locking lug 37 is of a length suchthat in one angular position of the locking shaft 35 (the broken lineposition of FIG. 9) the lug does not project beyond the periphery of thepin body 26 and, therefore, permits movement of the pin body through theapertures in the frame plates and through the roller bores. In adiametrically opposite angular position of the locking shaft 35, the lug37 projects outwardly beyond the periphery of the pin body 26 (the fullline positions of FIGS. 8 and 9). In the. latter position of the lockinglug, it serves to engage the bottom surface of the lower frame plate 11in opposition to the shoulder 34 to thereby prevent removal of the pinbody 26.

In order to facilitate manual operation of the locking shaft 35, it isprovided at its upper end with a radially projecting handle 40.Cooperating means may be provided on the handle 40 and the pin body 26for retaining the locking shaft 35 in locking position. The retainingmeans may take the form of a spring pressed ball 41 engageable with adimple formed in the under side of the handle 40.

Referring again to FIGS. 1, 2 and 3, the ram device 13 includes a fluidcylinder 45 having a hollow elongated piston or ram 46 reciprocabletherein. The cylinder 45 is supported by means of a cylinder block 47secured to one end of the cylinder and positioned between the mountingplates 10 and 11. The cylinder block is secured in place between theplates 10 and 11 by means such as the pins illustrated at 48, which passthrough the plates 10 and Ill and through complementary bores in thecylinder block. The pins 48 also register with an outer annular groove45a (FIGS. 1 and 2) formed on the cylinder 45 to retain the cylinder inthe block.

The cylinder 45 is closed at its end away from the cylinder block 47,and fluid may be admitted to this end of the cylinder through an inletfitting 49. Fluid, preferably air, under pressure, may be supplied tothe inlet fitting 49 and the interior of the cylinder 45 by means of ahand operated pump, or by other means if desired. The opposite end ofthe cylinder 45 is open, and the elongated piston or ram 46 projectsfrom the open end of the cylinder for connection with the bending shoestructure 14 previously referred to and described in detail hereinafter.The ram 46 is biased toward a retracted position in the cylinder 45 bymeans of a tension spring 50. The spring 50 is connected to the cylinder45 at its closed end by means-of a spring retaining nut 51 threaded intothe spring and threaded onto a spring retaining screw 52 which is inturn threaded into the cylinder end 45b. The spring 50 is connected in asimilar manner at its opposite end to the closed end of the ram 46 bymeans of a spring retaining nut 53 threaded into the spring and threadedonto a spring retaining screw 54 which is in turn threaded into thepiston end cap 46a. It will be celar that on the admission of fluidunder pressure to the interior of the cylinder 45 and the interior ofthe ram 46, the ram will be extended against the bias of the spring 50,and that on exhaust of fluid, the spring 50 will serve to retract theram.

The bending shoe structure 14 is detachably connected to the forceapplying ram, and is formed of a two-piece construction including anadapter 57 and a ending shoe 58. In pipe benders of the characterdescribed, ram forces are applied to a localized area of the bendingshoe structure, and must be transmitted to a relatively elongated pipeengaging face of the bending shot structure. Thus, considerabledifiiculty is encountered in constructing the bending shoe structure ina manner to provide sufiicient strength for receiving the localized ramforces and distributing these forces over the length of thepipe-engaging face while at the same time providing a practicalstructure economical to manufacture and sufficiently light to permitportability of the pipe bender as well as portability of the pipebending shoc structures which must be provided in different sizes andshapes for accommodating different pipes and for producing differentbends.

According to the present invention, the difliculties alluded to areovercome by the provision of the two-piece bending shoe structurereferred to. As illustrated, the adapter 57 is formed generally in theshape of a circular segment (FIG. 4) having a chordal side 59 forreceiving the ram forces, and an arcuate side 60 for transmitting theram forces to the bending shoe 58. The bending shoe 58 is formedgenerally in the shape of an arcuate segment (FIG. 1), having anarcuately curved pipe-engaging face 61, and an oppositely disposed face62 for receiving the ram forces transmitted by the adapter 57. Theinterengaging faces 60 and 62 of the adapter and the bending shoe arerelatively elongated as compared to the engaging surfaces of the ram andadapter so as to distribute the ram forces transmited to the adapterover a substantial length of the pipe bending shoe. An advantage of theconstruction illustrated lies in the fact that the adapter, connected tothe ram, may be constructed of a relatively heavy, high strengthmaterial which will withstand the stresses set up in transmission of theram forces to the bending shoe, while the bending shoe 58 and similarshoes of different sizes and shapes, may be readily detachable from theadapter and constructed of a relatively lightweight material, therebyrendering the pipe bender and the pipe bending shoes readily portablefor movement from place to place. In the construction illustrated, theadapter may be constructed of material such as steel, and the bendingshoes may be constructed of materials such as aluminum or magnesium.

Referring now particularly to FIGS. 4, 5 and 6 for a detaileddescription of the adapter, it is of somewhat hollow frame-likeconstruction. Centrally on its chordal side 59, the adapter is formedwith a recess in the form of a bore 64 which provides a socket forreceiving the projecting end of the force applying ram 46. The bore 64terminates in the adapter, providing a bottom or force receiving surface65 engageable with the end cap 46a of the ram for transmitting the ramforces to the adapter.

In order to detachably connect the adapter to the ram, the ram isprovided with an outer circumferential groove 66 (FIG. 2), and theadapter is provided with a pair of bores 67 and 68 (FIG. 4) transverseto the bore 64 and substantially tangential thereto on opposite sidesthereof, for receiving pins such as that illustrated at 69 (FIG. 1).

on the adapter.

faces 83a and 83b (FIG. 7).

The pins, when positioned in the bores 67 and 68, are

adapted to intersect with and be received in the annular groove 66 inthe ram so as to detachably connect the ram and adapter. Access may behad to the pins 69 for attaching the adapter to the ram through anaperture 79 formed in the upper frame plate It It should be understoodthat the connection aiforded by the pins 69 is provided principally foruse in retracting the bending shoe structure under influence of thespring 50. The bending shoe structure, including the adapter, is forcedoutwardly to bend the pipe principally by engagement of the end cap 46aon the ram with the force receiving surface 65 It will be seen that theforce of the ram is applied to the adapter over a relatively localizedarea.

In order to transmit the ram forces from the adapter .to the bendingshoe, and in order to permit detachable connection of the bending shoewith the adapter, the

arcuate side 69 of the adapter is recessed throughout its length, toleave spaced forwardly projecting web portions 71 and 72 (FIG. 6) whichare arcuately curved in plan view (FIG. 4). The forwardly facing,arcuately curved surfaces 71 and 72' on the web portions 71 and 72 formthe force transmittingsurfaces of the adapter, and are engageable withforce receiving surfaces of the bending shoe.

In order to provide a close fit of the bending shoe with the adapter soas to eliminate relative movement between the two when connected, theinner surfaces of each of the web portions 71 and 72 are each formedwith three separated lands 71a, 71b, 71c, 72a, 72b, and 720. These landsare raised relative to the adjacent surfaces of the web portions 71 and72 and are machined so that the bending shoe may be closely fittedbetween the lands on the web 71 and the lands on the web 72' asillustrated in FIG. 6.

By virtue of the hollow frame-like construction of the adapter, eventhough it may be constructed of relatively heavy, high strengthmaterial, its weight is reduced because of the hollow construction. Inorder to reinforce the adapter, it is formed on its upper side withlaterally spaced, upwardly and rearwardly projecting reinforcing webs74- and 75 which are integral with the adapter and extend rearwardlyfrom the line of engagement of the ram with the adapter. The undersideof the adapter is formed with similar reinforcing webs 76 and 77.

Referring now particularly to FIGS. 1, 6 and 7 for a detaileddescription of the bending shoe 58, the face 62 of the bending shoeadjacent the adapter is formed centrally with arcuate force receivingsurfaces adapted for engagement with the force transmitting surfaces 71'and 72 of the adapter. In order to form the force receiving surfaces onthe bending shoe, the shoe is formed with a rearwardly projecting web 81(FIG. 1) in the form of a circular segment adapted to project into therecess 70 formed in the adapter and terminating in a chordal side 82.The major portion of the web 81 is of a minor thickness substantiallythinner than the thickness of the recess 70, as best illustrated in-FIGS. 6 and 7. However, adjacent its projection from the bending shoeproper, the thickness of the web 81 is increased so as to just fitbetween the lands on the two web portions 71 and 72 of the adapter. Thethickened portion, designated 83 is genformed to provide upwardly anddownwardly facing sur- The upper surface 83a engages the lands 72a and720 on the upper web 72 of the adapter, and the downwardly facingsurface 83b engages the lands 71a and 710 of the lower web 71 of theadapter. Centrally, the thickened portion 83 includes a rearwardlyprojectipg lug 85 of a thickness also equal to the spacing between thelands on the upper and lower webs of the adapter, and positioned so asto fit between t the lands 71b and 7219.

In this manner, the bending shoe is positioned between thew'eb-s of theadapter in a erally arcuately shaped as best seen in FIG. 1 and is j bmanner to prevent twisting movement of the bending shoe relative to theadapter.

The thickened portion 83 of the Web 81 forms the arcuate side of the weband is joined integrally to the shoe proper in a manner formingshoulders which provide vertically disposed upper and lower surfaces 86and 87, arcuately curved in plan view as seen in FIG. 1, and adapted forengagement respectively with the force transmitting surfaces 71 and 72'of the adapters. The surfaces 86 and 87 thus form the force receivingsurfaces of the bending shoe. It will be appreciated that these surfacesare materially elongated relative to the localized inter-engaging forcetransmitting surfaces of the ram and adapter. Thus, the ram forces aredistributed evenly over a substantial portion of the bending shoe.

In order to detachably connect the bending shoe to the adapter, thecentral rearwardly projecting lug on the bending shoeis formed with avertical bore 89 (FIG. 6)

adapted to receive a connector pin. The overlying and 'to the pin 92 forconnecting and disconnecting the bending shoe through the access opening79 in the upper frame plate 10. i

As best illustrated in FIG. 1, the pipe-engaging face 61 of the bendingshoe 58 is arcuately curved to produce a desired radius of bend in alength of pipe to be bent. Also, the pipe-engaging face of the bendingshoe is recessed transversely throughout its length, arcuately,substantially semi-circularly, for receiving approximately half of theouter periphery of the pipe to be bent, as illustrated at 93,particularly in FIGS. 3 and 6.

In operation, a bending shoe of suitable proportions is selected andattached to the adapter. A length of pipe to be bent is then positionedbetween the upper and lower frame plates 10 and 11, against suitablyrecessed pipeengaging rollers 12. Fluid under pressure is then admittedto the ram cylinder, by means of a suitable handoperated air pump, orother means, to advance the bending shoe structure, the bending shoe 58engaging the midsection of the length of pipe to produce the desiredbend between the pipe-engaging rollers, in accordance with the curvatureof the bending shoe.

In order to assist the operator in determining when the desired degreeof bend has been produced, the bender is provided with indicia meansassociated with the upper frame plate 10 for indicating in degreescertain angles relative to a reference point and a reference line bothhaving a predetermined relationship to a length of pipe in the bender.The angles referred to are representative of selected degrees of pipebend. The indicia means referred to includes means defining on the uppersurface of the frame plate 10 a point aligned with the path of rammovement. As illustrated, the point is defined by an upright pin a4secured to the frame plate 10 and positioned in line with the axis ofthe ram, as seen in FIG. 1. Further, the upper surface of the frameplate 10 is provided with radially disposed indicia 94a, emanating fromthe point defined by pin 94, angularly spaced about the point, andangularly spaced from an imaginary line passing through the point andnormal to the path of ram movement.

The imaginary line passing through pins 94 and normal to the path of rammovement is parallel to the axis of a straight length of pipe positionedin the bender against pipe engaging rollers 12 before bending. After alength of pipe has been bent, it includes opposite end portions,normally of a length to project outwardly beyond the frame plates 10 and11, one each between a roller 12 and the ram structure 13 (FIG. 1).These end portions are larly spaced from the original axis of the pipeby an amount which, in degrees, is one half the total degree of bend inthe pipe. That is, if a bend of 60 is produced in the pipe, each of theopposite end portions of the pipe is angularly spaced by 30 from theoriginal axis of the pipe.

The radially disposed indicia 94a are positioned on the Side of saidimaginary line toward the ram device 14, and separate groups of themarkings 94a are provided on pposite sides of the path of ram movement.The indicia 94a are identified by degree markings, for example, 15, 30,45, 60, and 90, as illustrated, which indicate in degrees twice theangular spacing of the particular point 94a from the imaginary linepassing through pin 94 and normal to the path of ram movement. That is,the point 94a which is marked 60, is only 30 from the imaginary line.Thus, a line passing through pin 94 and the mark 94a identified as 60would be parallel to one tangent end portion of a length of pipe havinga 60 bend. The indicia provided enables an operator to sight along thisline by, for example, laying a 6' rule from the pin 94 to the 60 mark,and compare this line visually with the tangent end portion of the bentpipe to determine if the two appear to be parallel. Thus, the indiciaprovides a scale which enables an operator to readily determine roughlywhen the desired degree of bend is produced, without the necessity ofremoving the pipe from the bender for measurement by other means. Thisprovides a great saving in time where only approximate accuracy of bendis required.

The length of ram stroke is conveniently indicated by an elongated,graduated scale 95 (FIGS. 1 and 3) secured at one end, as by means of apin 96, to the adapter and movable with the ram and adapter relative toa reference point on the frame plate 10. After one length of pipe hasbeen bent as desired, sometimes by trial and error methods, and theproper length of ram stroke thereby determined for a particular bend,similar successive bends may be produced simply by reference to thescale on subsequent ram strokes. The scale permits the operator toreturn the ram and bending shoe to the desired position on eachoperation, to accurately produce the desired bend, without the necessityof relying on trial and error methods.

The pipe engaging face of the bending shoe 58 is recessed at 93 toreceive a substantial portion of the outer periphery of the pipe inorder to resist the tendency of the pipe to be deformed out of roundduring the bending operation. However, due to the tendency of the pipeto deform during the bending, the pipe becomes tightly wedged in thebending shoe, so that after the bending operation is completed,considerable difiiculty may be encountered in removing the length ofpipe from the bending shoe.

In order to provide for removal of the pipe from the bending shoe afterbending, the bending shoe is provided with bores adapted to receiveknock-out pins for dislodging the pipe. As illustrated, the bending shoeis formed with a pair of bores 97 and 93 (FIG. 1) spaced respectivelyapproximately one-fourth of the length of the bending shoe from itsopposite ends. The bores 97 and 98 extend transversely through thebending shoe, intersecting the semi-circular recess 93 for the pipe, theaxis of the bores being substantially tangent to the pipe recess at itsbottom, as illustrated particularly in FIG. 10. While the sectional viewof FIG. illustrates in detail the pipe removal means associated with thebore 97, it should be understood that the removal means associated withthe bore 98 is similar in all respects. As seen in FIG. 10, the bore 97is preferably fitted with a tubular hardened metal insert 99 which isrecessed as illustrated at 100 at the intersection of the insert withthe pipe recess 93 in the bending shoe. The tubular insert 99 is adaptedto receive a knock-out pin, generally designated 101 having a taperedend portion 102 adapted for engagement with the outer surface of thepipe P in the pipe recess. The tapered surface of the knock-out pinengages the pipe substantially tangentially, and on striking theknock-out pin to deliver an impact blow, as by means of a hand hammer,the knock-out pin is effective to dislodge the pipe. Engagement of theknock-out pin with the pipe substantially tangentially, as illustrated,serves to dislodge the pipe with no substantial injury or deformationthereof. The provision of bores for receiving two knock-out pins, bothlocated at off-center positions relative to the length of the pipe,serves to reduce the force required for dislodging the pipe.

In operation, after the pipe has been bent, if it is desired to test orcheck the bend for accuracy, the pressure in the ram cylinder 45 may berelieved enough to release the pressure of the pipe against the pipeengaging rollers 12. One or both of the rollers may be removed and thebending shoe 58 disconnected from the adapter 57 and removed from thebender. If the bend is satisfactory, the pipe may be dislodged from thebending shoe by use of the knockout pins 101 while the pipe and bendingshoe are out of the bender. If it is not necessary to check the bend foraccuracy, or if it is not necessary to remove the bending shoe from thepipe bender, as when the bending shoe projects outwardly beyond theupper frame plate 10 between the rollers 12 so as to expose the bores 97and 98, the pipe may be dislodged from the bending shoe by means of theknockout pins 101 when the pressure of the pipe against the rollers 12is relieved.

I claim:

1. In a pipe bender having a reciprocable force applying ram, incombination, an adapter connected to the ram, a bending shoe detachablyconnected to the adapter and having a pipe engaging face curved toproduce a desired pipe bend and recessed transversely throughout itslength, semi-circularly, to receive substantially half the outercircumference of the pipe to be bent, and means for removing bent pipefrom the semi-circular recess in the bending shoe when the shoe and pipewedged therein are detached from the adapter and removed from thebender, comprising, means defining a pair of bores in the bending shoe,each transverse to and intersecting the semi-circular recess in the pipeengaging face substantially tangentially at the bottom of the recess,and a pair of knockout pins, one receivable in each bore, and eachhaving a tapered end portion engageable tangentially with pipe in thebending shoe, so that when delivered an impact blow, the pin iseffective to dislodge the pipe.

2. For use in a pipe bender, a bending shoe having a pipe engaging facecurved to produce a desired pipe bend and arcuately recessedtransversely throughout its length, to receive a portion of the outercircumference of the pipe to be bent, means for removing a length ofpipe from the recess in the pipe bending shoe after bending, comprising,means defining a bore in the bending shoe transverse to and intersectingthe arc of the recess in the pipe engaging face substantiallytangentially at the bottom of the recess, and a knockout pin receivablein the bore and having a tapered end portion engageable tangentiallywith pipe in the bending shoe, so that on striking the pin, the pin iseffective to dislodge the pipe.

3. For use in a pipe bender having a reciprocable force applying ram, apipe bending shoe structure, comprising, an adapter of relatively heavy,high strength material in the shape of a circular segment connectablealong its chordtal side with the ram and having a continuous elongatedforce transmitting surface along its arcuate side, a plurality ofdifferent pipe bending shoes for bending pipes of different sizes andproducing bends of different curvatures, each of relatively lightweightlow strength material and of generally arcuate configuration having anouter arcuately curved pipe engaging face and an inner arcuately curvedforce receiving face detachably engageable with the force transmittingsurface of the adapter to distribute ram forces evenly over asubstantial length of the bending shoes.

4. For use in a pipe bender having a reciprocable force applying ram, apipe bending shoe structure, comprising, an adapter of relatively heavy,high strength material connectible to the ram and having an elongatedforce transmitting surface, a plurality of different pipe bending shoesfor bending pipes of different sizes and producing bends of differentcurvatures, each constructed of a relatively light weight, low strengthmaterial, each having a curved pipe engaging face recessed to receive aportion of the outer pipe surface, and each having an elongated forcereceiving surface detachably engageable with said force transmittingsurface, said force transmitting and force receiving faces each having alength at least approximately half the length of the pipe engaging faceto distribute the ram force evenly over a substantial length of theshoe, and means for detachably connecting said adapter to one of saidshoes.

5. In a pipe bender having a pair of plates mounted in overlying spacedapart relationship to receive a length of pipe therebetween, a pair ofpipe engaging rollers mounted between the plates in spaced appartrelationship, and a ram mounted for reciprocal movement between theplates toward and away from a midpoint between the two rollers, incombination, a pipe bending shoe structure for producing a bend in alength of pipe positioned between the plates and against the pipeengaging rollers, comprising, an adapter of relatively heavy materialconnected to the ram and having a continuous elongated curved forcetransmitting face, a unitary bending shoe of relatively light weightmaterial having a curved pipe engaging face to produce a desired bend,said shoe having a continuous elongated curved force receiving faceopposed to the pipe engaging face and detachably engageable with saidforce transmitting face, said force transmitting and force receivingfaces each having a length at least approximately half the length ofsaid pipe engaging face to distribute ram forces evenly over the entirelength of the interengaged force transmitting and receiving faces, and apin removably positionable in aligned recesses in the adapter and theshoe for detachably connecting the shoe to the adapter.

6. In a pipe bender having a frame, a pair of pipe engaging rollersmounted on the frame in spaced apart relationship, and a ram mounted onthe frame for reciprocable movement toward and away from a midpointbetween the two rollers, in combination, a pipe bending shoe structurefor producing a bend in a length of pipe positioned against the pipeengaging rollers, comprising, an adapter of relatively heavy, highstrength material connected to the ram and having a continuous elongatedcurved force transmitting face disposed normal to the path of rammovement, a unitary bending shoe of rela tively lightweight, lowstrength material having a curved pipe engaging face to produce adesired bend and having a continuous elongated curved force receivingface disposed normal to the path of ram movement and detachablyengageable with said force transmitting face, said force transmittingand force receiving faces each having a length at least approximatelyone half the length of said pipe engaging face to distribute ram forcesevenly over a substantial length of the pipe bending shoe, cooperatingsurfaces on the adapter and on the bending shoe disposed parallel to thepath of ram movement and detachably engageable to prevent twisting ofthe bending shoe relative to the adapter, and means for detachablyconnecting the bending shoe to the adapter.

7. For use in a pipe bender having a reciprocable force applying ram, apipe bending shoe structure, comprising, an adapter generally in theshape of a circular segment having an abuttable surface of limited andlocalized area centrally disposed along its chordal side for engagementwith the ram to transmit ram forces to the adapter, and having acontinuous elongated force transmitting face along its arcuate side, atleast approximately twice the length of said abuttable surface disposednormal to the plane of ram movement, and a unitary pipe bending shoe ofgenerally arcuate configuration having an outer arcuately curved pipeengaging face and an inner arcuately curved force receiving facedisposed normal to the plane of ram movement, complementary to saidforce transmitting face and detachably engageable therewith, said forcetransmitting and force receiving faces each having a length at leastapproximately half the length of said pipe engaging face fordistributing ram forces evenly over a substantial length of the bendingshoe.

8. A pipe bender, comprising, in combination, a pair of overlying spacedplates, a pair of spaced pipe engaging rollers between the plates,removable roller mounting pins one for each roller receivable in a borein the roller and in apertures in the plates for removably retaining therollers between the plates, a ram mounted for reciprocable movementbetween the plates toward and away from a line between rollers, anadapter connected to the ram, a pipe bending shoe having a pipe engagingface curved to produce a desired bend and arcuately recessedtransversely, to receive a portion of the outer pipe surface, meansdetachably connecting the bending shoe to the adapter to permit removalof the shoe and a pipe wedged therein from between said plates when oneof said roller mounting pins and the roller held thereby is removed fromthe mounted position between plates, and means for removing a length ofpipe from the recess in the bending shoe while the shoe is removed fromthe bender including, means defining a bore in the bending shoetransverse to and intersecting the arc of the recess substantiallytangentially at the bottom thereof, and a knockout pin receivable in thelast recited bore and having a tapered end portion engageable on thepipe in the bending shoe to wedge against and dislodge the pipe when thepin is struck a hammer blow.

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